JP4128140B2 - Manufacturing method of fiber sheet by extending tow and equipment therefor - Google Patents

Abstract

After yarns or tows (10) have been pre-spread and placed side by side substantially in a common plane, their surface is swept by at least one jet of air (22) displaced transversely relative to the longitudinal direction of the yarns or tows so as to obtain a substantially unidirectional sheet (20) that is uniform.

Description

[0001]
Background of the invention The present invention relates to producing a uniform fiber sheet by stretching tow. Said sheets are used in particular for reinforcing composite parts.
[0002]
It is well known to stretch a plurality of yarns or tows and to juxtapose the stretched yarns or tows to produce a relatively wide unidirectional fiber sheet. Stretching is done by passing a curved bar (or “banana” bar) or by passing an air spreader.
[0003]
The unidirectional sheets manufactured by the above method can be stacked in different directions and bonded together, for example, by needling, to form a multidirectional sheet. The sheet may be bonded by needling in the same way to other types of fiber fabrics, in particular woven fabrics, to constitute essentially bi-directional composite or multilayer fiber fabrics.
[0004]
To reduce the production cost of the fiber sheet, and especially when the fiber is carbon fiber, use commercially available thick yarn or tow that is much lower than the yarn with a lower price per unit weight. Is desirable.
[0005]
Nevertheless, the applicant has found that it is more difficult to produce a uniform sheet by stretching a thick yarn or tow and juxtaposing the stretched yarn or tow than with a thinner yarn. Found. It is difficult to prevent discontinuities (overlap or gaps) at the junction between the extended yarns or tows.
[0006]
Object and summary of the invention The object of the invention is to alleviate said drawbacks. For this purpose, the present invention is a method for producing a fiber sheet by stretching and juxtaposing yarns or tows, after pre-stretching the yarns or tows and arranging them side by side in a substantially common plane, A method for producing a fiber sheet is provided wherein the surface is swept with at least one air jet moving across the length of the yarn or tow so as to obtain a substantially unidirectional uniform sheet.
[0007]
Advantageously, the air jet moves back and forth from one end to the other end of a series of side-by-side yarns or tows while at the same time the yarn or tows move longitudinally.
[0008]
Preferably, the air jet is oriented substantially perpendicular to the plane of the yarn or tow.
[0009]
The method of the present invention provides uniformity to a unidirectional sheet by causing the filaments that make up the yarn or tow to vibrate by sweeping the yarn or tow with an air jet. Yarn or tow extension may be further performed during the sweeping operation.
[0010]
The sheet is preferably held in a state seen after air jet sweep, or at least primarily. This is advantageously achieved by passing a roller. The roller that contacts at least a portion of the sheet is manufactured from a material that exhibits a coefficient of friction that resists filament slippage that may lead to sheet narrowing or discontinuities. As an example, the material may be rubber or foam.
[0011]
The present invention also provides equipment capable of performing the method of the type comprising at least one device for pre-stretching the yarn or tow and means for arranging the yarn or tow downstream from the pre-stretch device. .
[0012]
According to the present invention, the equipment is at least one scavenging device using an air jet, which is disposed near the yarn or tow path downstream of the preliminary stretching device, and is added to the scavenging device. It further comprises a duct for supplying pressurized air, and a drive member for driving the scavenger across the path.
[0013]
BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood when the following description, given by way of non-limiting example, is read with reference to the accompanying drawings, in which: here,
FIG. 1 is a very schematic diagram of one aspect of the installation of the present invention;
FIG. 2 is an enlarged side view of a scavenging device using an air jet in the facility of FIG.
FIG. 3 is a side view taken along the line III-III in FIG.
FIG. 4 is a fragmentary diagram representing different aspects of the facility of FIG. 1, and FIG. 5 is a fragmentary diagram representing another different aspect of the facility of FIG.
[0014]
Detailed description of the invention In the installation of Figs. 1-3, a plurality of tows 10 pulled from a spool 12 are unrolled and pre-stretched by passing over a curved bar 14. In the example shown, each tow 10 passes over a continuous bar 14a, 14b, 14c and is in contact with the generator lines of the bar at its convex surface.
[0015]
The pre-stretched tows 10 are arranged side by side on the rollers 16 and follow a substantially vertically downward path from the rollers 16.
[0016]
Along this path, a series 18 of tows 10 arranged side by side is exposed to a sweep using an air jet in a direction extending across the toe movement direction D. The sweeping direction is preferably perpendicular to the direction D. That is, in the case of this figure, it is a horizontal direction substantially. In addition, the sweep direction is substantially parallel to the plane P formed by the series of tows 10.
[0017]
The sweeping is performed using an air ejection nozzle 22 supported by the support 24. The support is fixed at the end of the rod 25 of the actuator 26 and extends parallel to the plane P and is moved horizontally by a fixed horizontal rod 28 attached to the support 24 (only visible in FIGS. 2 and 3). To do. The flexible hose 30 introduces pressurized air to the nozzle 22.
[0018]
As an example, the actuator 26 is a pneumatic actuator. This is controlled to give the nozzle 22 a linear reciprocating motion from one end of the series 18 of tows 10 to the other end.
[0019]
In order to move the nozzle by horizontal reciprocation, a guide other than the above may be used. For example, the support 22 may be fixed to an endless belt that passes over the drive roller and a return roller at the stroke end of the nozzle 22. In this case, the driving roller is connected to a driving motor that alternately uses driving in one direction and driving in the opposite direction thereafter.
[0020]
After sweeping using an air jet, a uniform sheet 20 is obtained. The sheet has its width until it is fixed by passing it through at least one roller 32 made of a material exhibiting frictional properties such that at least part of the sheet in contact with the sides of the filaments resists sliding. And its uniformity are kept constant on at least a primary basis. As an example, the material is a foam of rubber or plastic material. Nevertheless, the adhesion between the roller 32 and the filaments of the sheet must be maintained with the restriction that the roller 32 prevents the filaments from floating from the sheet.
[0021]
In the path between the roller 16 and the roller 32, the sheet 20 is not fixed. The sheet tension is limited only by the sheet being pulled downward from the roller 32 against the weight of the individual spool 12.
[0022]
As schematically shown in FIG. 2, the air jet generated by the nozzle 22 deforms the sheet 20 and is therefore slightly away from the plane P. This deformation is applied to the filaments that make up the tow by vibrating in an unfixed path of the sheet between the rollers 16 and 32. Thereby, the filaments, in combination with the lateral movement of the nozzles 22, promote the distribution substantially uniformly over the width of the sheet.
[0023]
Even if the pre-stretched tow 10 is not used first, a uniform, substantially unidirectional sheet 20 is obtained even if the series of tows 18 are not arranged in close proximity to each other. FIG. 1 represents a pre-stretched tow 10 that leaves a gap 11 between the tows on the roller 16. It is the sweeping with the air jet that completes the extension of the tow. The sweep may be used to spread the sheet 20 over the full width of the series of tows 18.
[0024]
Originally, the air jet sweeping of the sheet 20 makes the sheet uniform even when care is taken to ensure that the tow 10 is placed on the roller 16 without leaving a gap between the tows 10. Continue to be effective.
[0025]
Passing the roller 32 contributes to holding the filament of the sheet in its associated position, thereby maintaining a uniform distribution of the sheet.
[0026]
After passing the roller 32, the sheet 20 is transported to the web forming station 36 where the unidirectional sheet 40 is fed, and the sheet 40 is continuously fixed with the continuously moving sheet 20, thereby providing a three-way sheet. 42 is obtained. The various layers making up this sheet 42 can be joined together by light needling at the needling station 44 and the resulting sheet can be stored on the take-up roller 46. Such stacking of multi-directional sheets by stacking unidirectional sheets in different directions and combining them together is well known.
[0027]
The tow 10 does not necessarily need to be pre-stretched or pre-expanded before being spread by uniforming and sweeping with an air jet, but said pre-stretching or pre-stretching separates the tow filaments from each other. Usually preferred. This is because the tow filaments may stick together somewhat due to the oiling operation.
[0028]
FIG. 4 represents a different embodiment in which the pre-extension of the tow 10 is performed by passing it through a slit tube.
[0029]
In the example shown, the tow 10 is initially divided into two groups. Every other tow passes through the first tube 50 upstream from the roller 16, while the other tows pass through the second tube 52 upstream from the roller 16 as well.
[0030]
Each tube 50, 52 is provided with a slit 50a, 52a formed through the tube wall and extending for a limited length parallel to the axis of the tube.
[0031]
One end of the tubes 50, 52 is closed, and pressurized air is supplied at the opposite end using pipes 54, 56.
[0032]
Each tow 10 passes through slits 50a, 52a provided in tubes 50, 52 extending perpendicular to the path followed by the tow 10.
[0033]
The air jet spouted from each slit extends the tow facing it.
[0034]
It is possible to pass the tow through a common slit tube, but the slit and the resulting tow to be stretched should not interfere with the extension of adjacent tows by the air jet used to stretch one tow. Must be placed far enough to ensure.
[0035]
FIG. 5 depicts another embodiment in which the sheet 20 is overlaid on a separately fed fiber fabric 60 (eg, a woven strip) after passing between rollers 32 and 34. The composite structure 62 formed of the sheet 20 and the woven fabric 60 is wound around a mandrel 64 to form an annular cylindrical fiber preform. The fiber layers superimposed on the mandrel 64 can be joined together by needling using a needle board 66 that extends along the mandrel bus and is driven by a reciprocating motion in the radial direction.
[0036]
It should be noted that in the present invention, a uniform sheet is constructed from a plurality of extended tows using simple and inexpensive means. The method of the present invention is preferably carried out using a thick tow. For example, uniform orientation of carbon fibers 30 cm to 50 cm wide using 48K carbon tow (ie, tow with 48,000 filaments) sold as “Panex 35-48K” by US manufacturer “ZOLTEK” The sheet was manufactured successfully.
[Brief description of the drawings]
FIG. 1 is a very schematic diagram representing one embodiment of the equipment of the present invention.
2 is an enlarged side view of an apparatus for extending using an air jet in the facility of FIG.
3 is a side view taken along the line III-III in FIG. 2;
FIG. 4 is a fragmentary diagram representing different aspects of the installation of FIG.
FIG. 5 is a fragmentary diagram representing another different aspect of the installation of FIG.
[Explanation of symbols]
10 ... Tow
12 ... Spool
14 ... Bar
16
32
34 Roller
18 ... A series of tow 10
20 ... Sheet
22 ... Air jet nozzle
24 ... Support
25 ... Rod
26 ... Actuator
28… Horizontal motion rod
30 ... hose
36 ... Web forming station
40 ... one-way sheet
42… 3-way sheet
44 ... Needling station
46 ... Winding roller
50
52 ... Slit tube
60 ... textile fabric
62 ... Composite structure of unidirectional sheet and fiber fabric
64 ... Mandrel
66 ... Needle board

Claims (4)

A method for producing a fiber sheet, the method comprising the following steps:
    Supplying a plurality of yarns or tows;
    Extending each of the plurality of yarns or tows (spreading) ;
    Arranging the stretched yarns or tows in a substantially coplanar manner in parallel and parallel to each other; and
    Thereafter, the surface of the extended yarn or tow arranged in parallel is swept with at least one air jet, during which the extended yarn or tow is parallel to the longitudinal direction of the yarn or tow. The air jet travels back and forth across the longitudinal direction of the yarn or tow from one end of the series of stretched yarns or tows arranged side by side to the other end, thereby Obtaining a substantially unidirectional uniform sheet;
The manufacturing method of the fiber sheet including this. The method of claim 1 , wherein the air jet is oriented substantially perpendicular to the plane of the yarn or tow. 3. A method according to claim 1 or 2 , wherein additional extension of the yarn or tow is achieved by air jet sweeping. After sweeping with an air jet, the resulting sheet includes passing a roller, wherein at least a portion of the roller in contact with the sheet maintains the sheet in an extended configuration. The method according to any one of claims 1 to 3 , wherein the method is made of a material exhibiting a coefficient of friction that resists sliding of a filament constituting the sheet.

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